The biggest draw for me was the "Ultimate Movie Watcher" feature, which takes advantage of all the stuff Blu-Ray can do that a regular DVD can't do. I started watching it last night, and found it to be really interesting. It felt a little like getting a glimpse at what will probably be the new standard for movie goodies. At some points the screen zooms back to a sort of chalkboard perspective with another "chalkboard" next to it, and the director stands between them and talks about the construction of various shots, or points out differences between composites. Elsewhere interesting elements are highlighted, or a timeline pops up showing the difference between the real world and the Watchmen world. Also, bubbles will pop up with featurettes that can be expanded on by pressing "enter" after which the main movie continues.
All these doo-dads come at an expense - it takes the player a little time to process the commands, during which it freezes, or a little yellow spinner plays.
It claimed that it would dispatch ninjas at the press of a button, but neither that nor the unicorn-summoning featurette worked. Maybe it's my player.